(1) Field of the Invention
The present invention relates to an elastomer composition containing a softening agent. More precisely, the present invention relates to an elastomer composition superior in appearance, bleed resistance, stability to environmental change and low temperature characteristics.
(2) Description of the Related Art
thermoplastic elastomer composition obtained by, so to speak, dynamic vulcanization, that is crosslinking during melt mixing of a radically crosslinkable elastomer and a radically non-crosslinkable resin such as polypropylene and a softening agent in an extruder in the presence of a radical initiator, is well known technology and widely used in applications such as automotive parts.
As such rubbery composition, a dynamic vulcanization technology using an olefinic elastomer manufactured by ethylene-propylene-diene (EPDM) has been known (JP-A-8-120127, JP-A-9-137001), but is not necessarily satisfied in the market due to inferior holding of a softening agent, remaining stickiness and poor low temperature characteristics.
On the other hand, a naphthenic hydrocarbon as a softening agent is also known and disclosed in U.S. Pat. No. 3,904,507. The above hydrocarbon has problems of inferior appearance caused by coloration and poor thermal and light stabilities, although it is superior in compatibility, in particular, with an olefinic elastomer and bleed resistance. Therefore, there is a need for a thermoplastic elastomer containing a softening agent, which is acceptable for practical use and is superior in appearance, bleed resistance, stabilities to environmental change and low temperature characteristics.